Electron population of Bader’s interatomic surfaces: relevance of estimates based on the electron density function values at critical points

The possibility to estimate the electron population of Bader’s interatomic surfaces using the electron density function values at the (3, −1) critical points is discussed taking the results of quantum chemical calculations of three model sets of isolated atomic aggregates as examples. A relevant method based on the approximation of normal distribution of the electron density over the interatomic surface is proposed and verified. The range of applicability of this approximation is considered using the results of calculations for a new model set.